DC should be punished with a time penalty.
First time DC must give a 10 minutes delayed penalty before you can enter a game again (before entering a lobby)
Second time DC must give a 20 minute penalty before you can enter a game again
Third time DC must give a 30 minute penalty.
Fourth time DC a 1 hour time penalty.
This resets everyday.
Its really not hard to program and I think it is very effective.

Comments
I disagree. I made a post about this yesterday, and this game is in no condition to punish dcs. I have stable connection, a good pc and run the game without many background apps. I still get disconnected from the servers quite often, so while it is true People Ragequit, a lot of times people lose connection/frames/resolution or the game down right CRASHES.
Depends, I would give at least two free DCs without any penalty, sometimes you just do it in the heat of the moment. Also, sometimes I crash, many people have this issue, the game would end up banning people unfairly.